This invention relates to the field of telecommunications, and more particularly to an event initiation bus and method for a telecommunications device.
Many telecommunications devices include backplanes for transmitting digital information between components of the devices. For example, a telecommunications switching system might include a backplane for transmitting digital data representing voice signals between cards associated with incoming and outgoing ports. Typically, such a system would also include one or more mechanisms to initiate certain types of events during operation of the system, for example, to reset a card, to electrically isolate a card from other cards, or to power a card on or off. Successful operation of the system in many instances will depend heavily upon the ability of these mechanisms to reliably initiate such events when they are desired, without inadvertently initiating such events when they are not desired, to meet the often stringent availability, flexibility, and other requirements placed on the system.
As the telecommunications industry continues to dominate the growth of the global economy, meeting availability, flexibility, and other requirements placed on switching and other systems has become increasingly important. High availability is generally considered as exceeding 99.999 percent availability, amounting to less than approximately five minutes of xe2x80x9cdown timexe2x80x9d per year, and generally requires a system to have the ability to autonomously handle and contain certain faults, such as failure of an event initiation mechanism, without immediate human intervention. High availability has increasingly become a de facto if not explicit competitive requirement for many telecommunications manufacturers.
However, prior event initiation techniques are often inadequate to meet these requirements. As the density of cards within telecommunications devices continues to increase, reliably initiating an event associated with one or more selected cards, while preventing an event from being undesirably initiated with respect these or any other cards, has become increasingly important. For example, using previous techniques, a redundant bus was typically required to limit propagation of a failure associated with a primary bus. Furthermore, even given a switchover from the primary to the redundant bus, one or more desired events may have gone uninitiated and one or more undesired events may have been initiated. Moreover, redundant buses typically increase the cost, increase the complexity, and reduce available pins and other resources within systems incorporating such techniques. Deficiencies of previous techniques may be particularly apparent when they are incorporated in high availability backplane environments of telecommunications devices.
According to the present invention, disadvantages and problems associated with event initiation strategies in a backplane environment of a telecommunications device have been substantially reduced or eliminated.
According to one embodiment of the present invention, a telecommunications device includes an event initiation bus, at least one card coupled to the bus that can execute an event, and at least one controller coupled to the bus that can communicate an event code value to the card using the bus. The event code value indicates the event is to be executed. The controller determines an event code value from the bus, compares the communicated event code value with the determined event code value, and transmits an event strobe signal to the card using the bus if the communicated event code value matches the determined event code value. The event strobe signal enables execution of the event and the card executes the event in response to the event code value and the event strobe signal. In a particular embodiment, the device is a switching unit having a high availability backplane environment.
The event initiation bus and related components of the present invention provide a number of important technical advantages over prior strategies, particularly within a high availability backplane environment of a telecommunications device. The present invention provides multiple layers of fault protection, including both the detection and handling of faults associated with the event initiation mechanism, helping to prevent single points of failure from propagating in the device, reduce down time, and satisfy high availability requirements. In particular, the present invention prevents a failure associated with an event initiation bus or a related component from causing a desired event to go uninitiated, from causing an undesired event to be incorrectly initiated, and from propagating. These benefits are accomplished without requiring a redundant bus configuration typically associated with prior event initiation mechanisms. As a result, the event initiation bus and related components of the present invention are well suited for incorporation in a wide variety of switching and other modern telecommunications devices. Other important technical advantages will be readily apparent to those skilled in the art.